Glycerol-agar: Growth non-pigment ed (Thompson, Jour. Bact., 26, 1933, 224). Broth: Moderate growth, favored by the addition of serum and peptone. Freshly isolated strains grow in the form of small granules which adhere to the walls of the tube or are collected on its bottom, leaving the broth fairly clear. On the surface, a fine, fragile pellicle is formed. Later genera- tions may grow rather diffusely. No change in reaction of medium. No odor. Coagulated serum and Loeffler serum: Good growth. A whitish, opaque laj'er is produced. No proteolysis. Litmus milk: Most strains produce no change, some strains produce a slight red- dening after 4 to 6 days. No coagulation. Potato: On natural potato, little or no growth; on potato rendered alkaline, a rather feeble, shining and yellowish gray layer may be formed. Indole produced in small amounts. Hydrogen sulfide not produced. Acid but no gas within 48 hours from glucose, maltose, sucrose and mannitol; some strains, after longer incubation, also produce acid from lactose, galactose, raf- finose, glycerol and salicin. No acid within 10 days from arabinose, rhamnose, adonitol, dulcitol, inositol, sorbitol or inulin. Nitrites not produced from nitrates. Aerobic, facultatively anaerobic; primary cultures are microaerophilic. Temperature relations: Optimum, 37° C. Slight growth at 20° C. Killed in m hours at 52°, in 1 hour at 54°, in 10 minutes at 62° and in 1 minute at 100° C.; on agar slants, survival for 10 to 12 da3's. No exotoxin is produced. Pathogenic for cattle and swine. A few cases have been reported in man. Rabbits and guinea pigs are slightly susceptible to inoculation. Serologically homogeneous (Haupt, Arch, f. wissen. u. prakt. Tierheilk., 67, 1934, 516); related serologically to Actinobacillus mallei Thompson (Thompson, Jour. Bact., 26, 1933, 225). Source and Habitat: Usually isolated from actinobacillosis of cattle. This condi- tion is often clinically diagnosed as "actino- mycosis". Lesions are found in soft tissues, usually in lymph nodes and in muscles of the tongue ("wooden tongue"), where granulomatous tumors are formed. Even- tually these break down to form abscesses, the pus containing small grayish white granules. 2. Actinobacillus eqiiuli (van Straaten, 1918) Haupt, 1934. {Bacillus nephriiidis equi Meyer, Transvaal Dept. Agr. Rept. Gov. Bac, 1908-1909, 122; Bacterium viscosum equi Magnusson, Svensk. Veterinartidskr., 1917, 81; also see Jour. Comp. Path, and Therap., 32, 1919, 143; Bacillus equuli van Straaten, Verslag van den Werksaamheden der Rijksseruminrichting voor 1916-1917, Rotterdam, 1918, 75; Bacillus equirulis, incorrectly attributed to van Straaten by de Blieck and van Heelsbergen, Tijdschr. v. Diergeneesk., 46, 1919, 496; Bacterium pyosepticum viscosum Miessner, Deutsch. tierarztl. Wochnschr., 29, 1921, 185; Shigella equirulis Edwards, Kentucky Agr. Exp. Sta. Res. Bui. 320, 1931; Haupt, Arch. f. wissen. u. prakt. Tierheilk., 67, 1934, 514.) e.quu'li. L. noun eguulus a small young horse, a foal; L. gen. noun equuli of a foal. Description taken largely from Edwards {op. cit., 1931). Rods, 0.3 to 0.4 by 0.5 to 0.8 micron, occurring singly, in chains and in filaments. The prevailing forms in rough, mucoid colonies are short, oval rods, and in smooth, non-mucoid colonies, long filaments and chains prevail. Capsules have been de- scribed, but their existence is uncertain. Non-motile. Gram-negative. Gelatin colonies : Similar to those on agar. No liquefaction. Agar slant: Grayish white, viscid growth covering the surface. Viable 8 to 10 days. Infusion-peptone-agar: Good growth. Colonies 3 to 6 mm in diameter in 48 hours. In primary cultures rough type colonies prevail with lobulated surface and mucous or stringy consistency; in later generations smooth type colonies with glistening smooth surface and of soft (non-mucous) consist- ency prevail. Broth: Masses are formed on the wall of the tube. At times a thin, grayish pellicle is formed. Grayish, tough, ropy sediment. Eventually there is diffuse turbidity which is highly viscous. Viability, 2 to 4 weeks.
